№1
#include <iostream>
using namespace std;

int a (int);
int b (int);
int c (int);
int d (int);
int e (int, int, int);

int main(){
    int year, f;
    cout << "Введите год" << endl;
    scanf("%d",&year);
    
    int a_val = a(year);
    int b_val = b(year);
    int c_val = c(year);
    int d_val = d(a_val);
    int e_val = e(b_val, c_val, d_val);
    
    f = d_val + e_val;
    
    if (f <= 26){
        cout << "Пасха будет ";
        cout << 4 + f;
        cout << " апреля" << endl;
    }else{
        cout << "Пасха будет ";
        cout << f - 26;
        cout << " мая" << endl;
    }

}

int a (int year){
    return year % 19;
}

int b (int year){
    return year % 4;
}

int c (int year){
    return year % 7;
}

int d (int a){
    return (19 * a + 15) % 30;
}

int e (int b, int c, int d){
    return (2 * b + 4 * c + 6 * d + 6) % 7;
}



№2
#include <iostream>
#include <cmath>
using namespace std;

int main(){
    
    float x, f = 1;
    int n, ni;
    
    cout << "Введите x:" << endl;
    scanf("%f",&x);
    cout << "Введите n:" << endl;
    scanf("%i",&n);
    
    if (n >= 0){
        for (ni = 1; ni <= n; ni = ni + 1){
            f = f * x;
        }
    }else{
        n = abs(n);
        for (ni = 1; ni <= n; ni = ni + 1){
            f = f / x;
        }
    }
    
    cout << f << endl;
}



№3
#include <iostream>
#include <cmath>
using namespace std;

float factorial(int n){
    float f = 1;
    for (int i = 1; i <= n; i++){
        f = f * i;
    }
    return f;
}

int main(){
    float cosinus = 1;
    float x, temp, eps = 0.0001;
    int n = 1;
    cout << "x = ";
    scanf("%f", &x);
    
    do {
        temp = (pow(-1, n) * pow(x, 2*n)) / factorial(2*n);
        cosinus = cosinus + temp;
        n++;
    } while (abs(temp) > eps);
    
    cout << cosinus << endl;
    cout << cos(x) << endl;
}

